You would pay no Capital Acquisitions Tax as the value of €200,000 is below your threshold.
There are no tax implications for your mother. As it was her home, it is exempt from Capital Gains Tax.
Do you have a mortgage on your own home. Is there equity in it? Why not sell it to fund the renovations?
If you have a tracker on it, you could port the tracker to buy your mother's house.
Some potential problems down the road - these happen in practice although you probably couldn't imagine them happening to you
You and your husband split up and he wants you to buy him out of the house. After all you own it jointly. OK, if it's signed over to you, it will improve your position. But as it is the family home, he might have a claim on it.
I know of one tragic case where the mother signed the family home over to the daughter and her husband. Everything went absolutely fine until the daughter died suddenly. Mother and son in law lived happily ever after... until son in law met a new woman and wanted to marry her. He had no choice but to put the mother out of the house.
So maybe remortgage your existing home to do the work, and leave your mother's home in her name.
Brendan